The invention set forth in this specification pertains to new and improved apparatus for fluid treatment by electron emission or corona discharge. Although the invention is intended to be beneficial in connection with the treatment of any fluid susceptible to treatment by electron emission at this time it is primarily intended to be utilized in connection with the production of ozone from either pure oxygen or an oxygen containing gas mixture. The complete invention set forth is considered to embody a number of facets which can be separately utilized in an apparatus for the purpose indicated but which are of such a character that they are preferably utilized in conjunction with one another.
It is, of course, conventional to construct an apparatus for use in treating a fluid by electron emission which includes a first electrode, a dielectric located alongside of and spaced from the first electrode so as to define a gap between the first electrode and the dielectric, a second electrode adjacent to the dielectric and an appropriate inlet and outlet leading to the gap so that a fluid may be circulated through the gap. In the operation of such a device an appropriate current is applied to the electrodes so as to cause periodically reversing electron flow or emission in the gap as the fluid being treated is circulated through the gap. Although an apparatus of this type can be utilized in treating many different types of fluid it is believed that this type of apparatus is primarily utilized at the present time in connection with the treatment of either pure oxygen or an oxygen containing gas mixture so as to form ozone.
An apparatus consisting only of the parts delineated in the preceding paragraph is frequently referred to as a "cell". It is conventional to use a plurality of such cells either in parallel with one another or in series with one another. Further the sizes of such cells may be varied within comparatively wide limits. It is considered that such cells are most commonly constructed so that the various parts enumerated in the preceding are flat and disposed parallel to one another. It is, however, known to manufacture such cells of a cylindrical configuration so that various parts of them are concentric to one another.
In the use of any cell in connection with the treatment of a fluid by electron emission certain reasonably obvious factors are considered to be of paramount importance. One of these is efficiency and more specifically efficiency in terms of the amount of a desired product formed as a result of the treatment within the cell per unit of power consumed. Thus, for example, the efficiency of an apparatus or cell for producing ozone is measured in the amount of ozone produced per unit of power used in the production of ozone. This matter of cell efficiency is quite complex and is obviously related to the way a specific electron emission cell is utilized. The efficiency of a cell will vary in accordance with the manner in which power is supplied to the cell and other factors which are considered relatively unimportant to an understanding of the invention.
Another factor which is quite important in connection with any apparatus or cell for use in fluid treatment be electron emission concerns how long the cell will operate without breaking down as it is used. From a practical standpoint it is undesirable to utilize an electrically efficient cell or apparatus if such cell or apparatus has to be frequently taken apart and repaired so that it will operate satisfactorily. This matter of the useful life of an apparatus or cell as indicated is relatively involved because the conditions within an apparatus or cell of the type under consideration are normally such as to promote comparatively rapid failure of the dielectric within the cell.
This can be easily illustrated with reference to an apparatus or cell for producing ozone. Ozone is a highly reactive gas which is well know to be detrimental to normal organic compounds and materials. The conditions set up within an apparatus or cell as noted as the result of the use of relatively intense, constantly reversing electron flow tend to promote deterioration in normal or conventionally used dielectrics. When such a dielectric is affected so that a flaw and/or discontinuity penetrates it an apparatus as noted is no longer satisfactory for its intended purpose.
It is considered that to a degree the undesirability of prior cells for use in fluid treatment by electron emission is suggested or indicated by the lack of significant widespread utilization of fluid emission in the production of ozone, particularly since it is well recognized that ozone possesses many advantages for many oxidizing purposes, such as for example, in purifying drinking water, treating sewage effluent and the like. Regardless of whether or not this is the case it is considered that there is a need for new and improved apparatus for use as a reaction unit or cell in the treatment of fluid by electron emission. More specifically it is considered that there is a need for cells which can be efficiently utilized over prolonged periods without attention.